import {
  differenceInDays,
  differenceInHours,
  differenceInMinutes,
  format,
  formatDistanceToNow,
  formatISO,
  fromUnixTime,
  getUnixTime,
  getYear,
  parseISO
} from "date-fns";

const formatISONoTimezone = date => {
  if ( !date ) {
    return "";
  }
  const formattedISODate = formatISO( date );
  if ( !formattedISODate ) {
    return "";
  }
  // Always take the first part of the time/date string,
  // without any extra timezone, etc (just "2022-12-31T23:59:59")
  return formattedISODate.substring( 0, 19 );
};

// two options for observed_on_string in uploader are:
// 2020-03-01 00:00 or 2021-03-24T14:40:25
// this is using the second format
// https://github.com/inaturalist/inaturalist/blob/b12f16099fc8ad0c0961900d644507f6952bec66/spec/controllers/observation_controller_api_spec.rb#L161
const formatDateStringFromTimestamp = timestamp => {
  if ( !timestamp ) {
    return "";
  }
  const date = fromUnixTime( timestamp );
  return formatISONoTimezone( date );
};

const createObservedOnStringForUpload = date => formatDateStringFromTimestamp(
  getUnixTime( date || new Date( ) )
);

const displayDateTimeObsEdit = date => date && format( new Date( date ), "PPpp" );

const timeAgo = pastTime => formatDistanceToNow( new Date( pastTime ) );

const formatApiDatetime = ( dateString, t ) => {
  if ( !dateString || dateString === "" ) {
    return t( "Missing-Date" );
  }
  const hasTime = dateString.includes( "T" );
  const date = parseISO( dateString );

  if ( hasTime ) {
    return format( date, t( "datetime-format-short" ) );
  }
  return format( date, t( "date-format-short" ) );
};

const formatObsListTime = date => {
  const dateTime = "M/d/yy h:mm a";
  if ( typeof date === "string" ) {
    return format( parseISO( date ), dateTime );
  }
  return format( date, dateTime );
};

const formatIdDate = ( date, t ) => {
  const d = typeof date === "string"
    ? parseISO( date )
    : new Date( date );
  const now = new Date();

  const days = differenceInDays( now, d );

  if ( days <= 30 ) {
    // Less than 30 days ago - display as 3m (mins), 3h (hours), 3d (days) or 3w (weeks)
    if ( days < 1 ) {
      const hours = differenceInHours( now, d );
      if ( hours < 1 ) {
        const minutes = differenceInMinutes( now, d );
        return t( "Date-minutes", { count: minutes } );
      }
      return t( "Date-hours", { count: hours } );
    } if ( days < 7 ) {
      return t( "Date-days", { count: days } );
    }
    return t( "Date-weeks", { count: parseInt( days / 7, 10 ) } );
  }
  if ( getYear( now ) !== getYear( d ) ) {
    // Previous year(s)
    return format( d, t( "Date-short-format" ) );
  }
  // Current year
  return format( d, t( "Date-this-year" ) );
};

const formatUserProfileDate = ( date, t ) => format( parseISO( date ), t( "date-format-long" ) );

export {
  createObservedOnStringForUpload,
  displayDateTimeObsEdit,
  formatApiDatetime,
  formatDateStringFromTimestamp,
  formatIdDate,
  formatISONoTimezone,
  formatObsListTime,
  formatUserProfileDate,
  timeAgo
};